Macrophage apoptosis induced by aqueous C60 aggregates changing the mitochondrial membrane potential

• Macrophage incubated with nC60 aggregates showed a decrease in cell viability.
• nC60 aggregates induced macrophage apoptosis.
• nC60 aggregates caused the increase of ROS in macrophage cells.
• nC60 did not cause lipid peroxidation of macrophage cell membrane.
• Mitochondrial membrane potential was depleted when cells incubated with nC60.

Fullerenes have been applied to various fields in recent years for their unique physicochemical properties. C60's potential environmental and health risks are therefore being investigated. This work presents the cytotoxicity of aqueous C60 aggregates (nC60) by using the mouse peritoneal macrophage (RAW264.7) as a model biological system. Cells incubated with nC60 showed a decrease in cell viability, and the quantities of cell apoptosis increased significantly in a dose-dependent and time-dependent manner. By TEM imaging cells were observed to be asymmetric and shrunken compared to control cells. nC60 was adsorbed onto the plasma membrane and apparent phagocytosis was observed after a 24 h exposure. The intracellular reactive oxygen species (ROS) were quantified with the dichlorofluorescein diacetate (DCFH-DA) detection assay kit by flow cytometry and found to increase in treated cells. Membrane damage and lipid peroxidation were not observed, since both intracellular and extracellular MDA showed no variation. Detection of the mitochondrial membrane potential (MMP) by JC-1 assay kit showed that MMP had an obvious dose-dependent loss. We speculate that the nC60 aggregates induced apoptosis of macrophage by changing the mitochondrial membrane potential.